A conventional ECU network system includes an ECU mounted in each part of a vehicle and connected through a communication network such as an in-vehicle LAN or the like. Inherent IDs are allocated to respective ECUs even when these ECUs have the same function from the viewpoint of necessity on communication managements. FIG. 25 shows the construction of such a related art ECU network system. In this ECU network system, a control ECU 1 serving as a master for communication processing and plural ECUs 2A, 2B, 2C, 2D serving as slaves are connected to a communication network 3 such as an in-vehicle LAN or the like through wire harnesses 4A, 4B, 4C, 4D.
The four slaves ECUs 2A to 2D are arranged in the doors of the vehicle, and monitor the open/close state of the doors and the lock/unlock state of the doors. These slave ECUs correspond to the four doors at the left front side (shown as LF), the right front side (shown as RF), the left rear (left rear seat shown as LR) and the right rear (right rear seat shown as RR). For example, different IDs such as a left front ID “ECU—1”, a right front ID “ECU—2”, a left rear ID “ECU—3” and a right rear ID “ECU—4” are allocated to the respective slaves ECUs 2A to 2D in accordance with the position of each door.
Patent Document 1 (JP-A-2000-151538) discloses an example of such a communication network system. This system discloses multiplexing plural real-time data output from one signal source and transmitting/receiving the data by one node. Therefore, this disclosed approach has no direct relation to the background technique of the present invention.
However, advance allocation of different IDs to the four slaves ECUs 2A to 2D connected to the same network means that when parts are managed, these parts are managed while different part numbers are also allocated to the same type of ECUs, and thus the management is cumbersome.
A manner of dynamically setting IDs on the network may be considered as a means of avoiding the presetting of different IDs to the plural slaves ECUs 2A to 2D. For example, an approach is known in which a dedicated terminal is provided for identifying each ECU and decoding data set by these terminals to determine ID. However, this approach has the drawback of requiring the number of necessary terminals and the number of signal lines connected to these terminals to increase as the number of ECUs connected to the network increases.